Alkyl triazeno uracil compounds and method of preparation thereof

ABSTRACT

5-ALKYL TRIAZENO URACIL COMPOUNDS AND DERIVATIVES THEREOF WERE SYNTHESIZED BY REACTING AN ALKYL AMINE SUCH AS DIMETHYLAMINE WITH A METHONAL ADDUCT OF 5-DIAZOURACIL AND NUCLEOSIDES THEREOF, UNDER STRINGENT REACTION CONDITIONS TO YIELD THE DESIRED COMPOUNDS. These alkyl triazeno uracil compounds have the structure ##STR1## wherein R is hydrogen or a carbohydrate group, particularly a pentose or hexose monosaccaride such as ribose, arabinose, glucose, and the like, and R&#39; and R&#34; are lower alkyl groups having one to four carbon atoms and wherein R&#39; and R&#34; may be the same or different alkyl groups. The compounds of this invention have been found especially effective as antibacterial and antifungal agents and in inhibiting carcinoma growth in animal tissue.

This is a continuation, of application Ser. No. 282,362, filed Nov. 6, 1972, now abandoned.

BACKGROUND OF THE INVENTION

The structures of 5-diazouracil, 5-diazouridine and 5-diazo-2'-deoxyuridine have been the subject of several investigations. Originally, 5-diazouracil was prepared by decarboxylation of 5-diazoorotic acid(Behrend and Ernert, as reported in Ann. Chem., 258, 347 (1890). Several compounds were isolated in the Behrend and Ernert investigation, including an anhydride, a hydrate and an ethanol adduct of 5-diazouracil. These compounds were assigned, respectively, the following structures: ##STR2##

The assigned structures, however, have been reinvestigated. See Thurber and Townsend, A Reinvestigation of the Structure for 5-diazouracil, 5-diazouridine, 5-diazo-2'-deoxyuridine and Certain Related Derivatives by Proton Magnetic Resonance Spectroscopy, J. Hetero, Chem., 9, 629, (1972). This reinvestigation was conducted because the above-assigned structures failed to explain certain properties of 5-diazouracil and related compounds, and because 5-diazouracil and related compounds failed to react under conditions typical for diazo compounds.

SUMMARY OF INVENTION

The compounds of this invention are generically 5-alkyl triazenouracil, -uridine and -2'-deoxyuridine compounds having the structure ##STR3## wherein R is hydrogen or a carbohydrate group, particularly a monosaccaride such as ribose, arabinose, glucose, and the like group and R' and R" are lower alkyl groups containing one to four carbon atoms, especially methyl and ethyl groups and wherein R' and R" may be the same or different groups.

Specific compounds include: 5-(3, 3-dimethyl-1-triazeno) uracil having the formula: ##STR4## and uridine compounds such as 5-(3, 3-dimethyl-1-triazeno) uridine having the formula: ##STR5## and 5-(3, 3-dimethyl-1-triazeno) -2'-deoxyuridine having the formula: ##STR6##

Although the above identified compounds are illustrative of compounds where R of structure IV is either hydrogen, ribose, or 2' deoxyribose, other carbohydrate groups, particularly monosaccaride groups are within the scope of the invention. Preferred carbohydrate compounds are those of eight carbons or less, particularly of six carbons or less wherein the R group is a monosaccaride. Monosaccarides which are stable adducts to the basic pyrimidine structure and which are sufficiently small to avoid sterically interfering with the desired reactions include ribose, including 2-deoxyribose, glucose, arabinose, pentose and hexose groups.

These compounds are of particular interest inasmuch as they have exhibited antibacterial, antifungal and anticancer activity.

The compounds of this invention are formed by reacting a pyrimidine compound, that is, a uracil or uridine, having the structure: ##STR7## with a dialkylamine, including cyclic amines, for example, diethylamine, diproplyamine, dimethylamine, methyl ethylamine, methyl propylamine, ethylbutylamine, morpholine and the like. The reaction is preferably conducted at a temperature of above about 10° C. and preferably at temperatures at above at least about 20° C. The reaction may be conducted at atmospheric pressure, although super-atmospheric pressures are generally preferred to shorten the reaction time. Reaction under super-atmospheric conditions is generally conducted by placing the reactants in a sealed container, e.g. a laboratory bomb, capable of withstanding high pressures and placing same in an autoclave. The reaction pressure results from the increased temperature of the materials and the expulsion of gaseous reactants and reaction products. The reaction if conducted at ambient temperatures using a condensor if necessary to maintain a constant temperature condition.

The reaction proceeds well under fusion conditions, although solvents may be utilized if desired. Preferable solvents include ethylacetate, methylacetate and similar mildly polar solvents. Other solvents include higher alkyl acetates and alkyl ethers such as methyl ethyl ether, diethyl ether and the like. Mildly polar solvents such as ethylacetate and methylacetate are preferred inasmuch as aromatic solvents do not provide sufficient solubility of reactants to be useful while more polar solvents such as water, methanol, ethanol, acrylonitrile and the like cause ionization, resulting in a reaction which does not produce the desired compounds. Reaction under fusion conditions is generally preferred since the necessity of a separate solvent is eliminated.

The reaction temperature range is from about 10° C. to about 80° C. and preferably from about 20° C. to about 60° C. At temperature conditions higher than about 80° C., especially if a fusion reaction is being conducted, too much of the uridine or uracil reactant becomes soluble in the dimethylamine which can result in ionization yielding a product other than the desired product.

These reaction conditions are considered stringent for diazo compounds inasmuch as reactions involving diazo compounds are usually conducted about or below 0° C. At temperatures higher than about 0° C. diazo compounds are typically very unstable. It has been concluded that the stringent conditions are required to break the C--O--C bond at the six position (Structure VIII) without causing ionization to occur at the nitrogen atom in the three position (Structure VIII).

The triazeno compounds produced according to this invention have been found to be stable up to their respective melting points unless some of the alkylamine reactant is occluded. Occluded alkylamine, such as dimethylamine, tends to cause ionization and degradation of the reaction product.

The preparation of selected compounds of this invention is illustrated by the following examples:

EXAMPLE I Preparation of 5-(3, 3-Dimethyl-1-triazeno) uracil

To 2.5 grams of 5-Diazouracil-methanol adduct (XI) was added 84 milliliters of ethylacetate at room temperature in a pressure bottle. This suspension was cooled to 0° C. and 10 milliliters of anhydrous dimethylamine were then added. The pressure bottle was sealed and heated in an oil bath of 40°-43° C. for 4 hours and then allowed to stand at 5° C. for 18 hours. The white solid was collected by filtration, washed with 10 milliliters of ethylacetate at room temperature, dissolved in 125 milliliters of methanol at room temperature and then stirred with Norit (100 milligrams) for 15 minutes. The Norit was removed by filtration and the filtrate concentrated (not to dryness) keeping the temperature below 20° C. to give a thick suspension. The precipitate was collected by filtration, washed with ethylacetate (15 milliliters) and then allowed to dry at room temperature to give 1.9 grams of product having a melting point of 162°-164° C., decomposing with explosion. An additional 0.56 grams of product was obtained from the methanol filtrate by evaporation to dryness in vacuo, to give a total product recovery of 2.46 grams (90% yield). A small sample was dissolved in methanol, treated with Norit, the Norit removed by filtration and the filtrate evaporated to dryness. This solid was dired at 100° C. under 0.2 Tr vacuum over P₄ O₁₀ to afford an analytical sample, melting point 166°-167° C.;

uv: λ _(max) ^(MeOH), 263 nm (ε 16, 500).

Anal. Calcd. for C₆ H₉ N₅ O₂ : C, 39.34; H, 4.95; N, 38.23. Found: C, 39.39; H, 4.98; N, 38.39.

EXAMPLE II Preparation of 5-(3, 3-Dimethyl-1-triazeno) uridine (VI).

To 10.0 grams of 0^(5') -6(S)-cyclo-5-diazouridine was added 200 milliliters of ethylacetate and this reaction mixture divided equally into two separate pressure bottles. These reaction mixtures were then cooled to 0° C. in an ice-salt bath and 25 milliliters of anhydrous dimethylamine added to each vessel. The pressure bottles were sealed, covered with aluminum foil and allowed to stand at room temperature for 1 hour with occasional shaking. They were then heated in an oil bath at 52°-55° C. with vigorous stirring for 4 hours. The source of heat was removed, the oil bath allowed to slowly cool and the reaction mixture stirred for an additional 16 hours.

The pressure bottles were cooled to 0° C and the solutions combined. The oil which remained in the reaction vessels was dissolved in a minimum amount of methanol (approximately 50 milliliters) and this was added to the ethylacetate solution. This solution was evaporated in vacuo in an oil while maintaining the temperature below 30° C. The oil was triturated with ethylacetate (50 milliliters) and scratching with an aluminum spatula produced a light yellow solid which was collected by filtration and washed with ethylacetate (25 milliliters). An additional quantity of product was obtained from the filtrate by repeating the above procedure (evaporation and trituration) to give a total yield of 10.6 grams, which softened at 122°-126° C. and melted at 130°-138° C.

This solid was recrystallized from boiling acetonitrile (500 milliliters) with sufficient methanol added to effect a clear solution. Two crops were obtained by isolation, volume reduction to 250 milliliters in vacuo and the addition of 20 milliliters of ethylacetate to give 9.2 grams of product (79% yield) having a melting point of 136°-138° C. An analytical sample was obtained by recrystallization from acetonitrile and dried in an Abderhalden apparatus over isopropanol at reflux temperature of 1.5 hours over P₄ O₁₀, melting point 170°-172° C; uv: λ _(max) ^(MeOH), 322 nm (ε 11,800), 271 nm (ε 10,700).

Anal. Calcd. for C₁₁ N₁₇ N₅ O₆ : C, 41.91; H, 5.43; N, 22.21. Found: C, 41.96; H, 5.49; N, 22.12.

EXAMPLE III Preparation of 5-(3, 3-Dimethyl-1-triazeno)-2'-deoxyurdine (VII).

Anhydrous dimethylamine (10 milliliters) was added to 150 milligrams of O⁵ '-6(S)-cyclo-5-diazo-2'-deoxyuridine and the solution stirred and allowed to reflux (dry ice-acetone condensor) at room temperature for 1.5 hours. The solution was evaporated to dryness in vacuo (38°) to give a fine white crystalline material. Ethylacetate (3 milliliters) was added and the crystals collected by filtration, washed with 6 milliliters of ethylacetate and dried at room temperature to give 162 milligrams (92%) of product, melting at 168°-169° C. with decomposition. A small sample (155 milligrams) was recrystalized, with charcoal, from 15 milliliters of acetonitrile. This was dried under vacuum at room temperature for 20 hours using Drierite as the dessicant to give 146 milligrams of product melting at 170°-171° C. with decomposition; uv: λ _(max) ^(MeOH), 330 nm (ε 9,400), 271 nm (ε 8,000).

Anal. Calcd. for C₁₁ H₁₇ N₅ O₅ : C, 44.15; H, 5.73; N, 23.40. Found: C, 44.20; H, 5.79; N, 23.77

The compounds of this invention have utility as antifungal, antibacterial, anti-tumor and carcinoma inhibiting agents. Specific utility is illustrated in the following tables:

                  TABLE I                                                          ______________________________________                                         Activity of 5-(3, 3-dimethyl-1-triazeno) uridine                                      Dose                                                                    Tumor  mg/kgm    Survivors  Cures  T/C                                         ______________________________________                                         LE     400       6/6        --     112                                         LE     400       6/6        --     147                                         LE     400       6/6        --     103                                         LE     400       6/6        --     174                                         PS     300       6/6        4      300                                         PS     150       6/6        6      300                                         PS     75        6/6        6      300                                         PS     37.5      6/6        6      300                                         ______________________________________                                          The above abbreviations have the following meaning:                            LE - Leukemia L-1210                                                           PS - Lymphocytic leukemia                                                      T/C - Test/Control                                                       

The above data was obtained according to conventional in vivo testing procedures. Each specimen was injected with a certain type of leukemia which is known to be fatal within a known time, e.g. 10 days for lymphocytic leukemia. Each specimen was then administered a certain dose of 5-(3, 3-dimethyl-1-triazeno) uridine, for example, a certain dosage amount depending upon body weight of the specimen.

The designation "Survivors" means that the compound was not toxic, i.e. it was not fatal to the specimens at any of the reported dosages. The designation "cures" means that specimens were still surviving at the end of the test period; 30 days in this instance. The "T/C" designation is an activity level; e.g., for leukemia L-1210 any activity over 125 is considered to indicate an active compound.

The instant compound proved very effective against lymphocytic leukemia since substantially all test specimens were living at the end of the 30 day test period, at which time the specimens were sacrificed for further examination. Thus, the test specimens had a 300% life expectancy when compared with control specimens.

5-(3, 3-Dimethyl-1-triazeno) uracil and 5-(3, 3-diethyl-1-triazeno) uracil were screened for antibacterial and antifungal activity. The results are illustrated in Table II.

                  TABLE II                                                         ______________________________________                                         B      A        COMPOUND                                                       ______________________________________                                                4+       Serratia marcescens                                            4+     6+       Pseudomonas aeruginosa                                         5+     6+       Staphylococcus aereas                                          5+     6+       Escherichia coli                                               5+     6+       Streptococcus faecalis                                                5+       Klebsiella pneumoniae                                          5+     6+       Proteus vulgaris                                                       +       Aspergillus niger                                                      +       Candida albicans                                                +      +       Cryptococcus diffluens                                          +      +       Sacchromyces cerevisiae                                        ______________________________________                                          Compound A 5-(3,                                                               Compound B 5-(3,3 -diethyl-1-triazeno)uracil                             

The above activities were determined in vitro in a conventional manner for classifying antibacterial and antifungal activities. The plus (+) designation indicated activity, while the number associated therewith provides a degree of activity, with six being the highest activity attainable.

Both of the tested compounds showed significant activity against a number of common bacteria and fungi.

ASSIGNMENT OF STRUCTURES

The structures of 5-diazouracil, 5-diazouracil methanol adduct and 5-diazouracil hydrate were reinvestigated by proton magnetic resonance techniques. A complete description of the procedures and analysis appears in J. Hetero Chem., 9, 629 (1972), the text of which is incorporated herein by reference.

The investigation resulted in the following structures being assigned, respectively, for 5-diazouracil, 5-diazouracil hydrate and 5-diazouracil methanol adduct: ##STR8##

The structure XI assigned to the methanol adduct of 5-diazouracil offered the possibility of several different results upon reaction with a nucleophile, e.g., the nucleophile could (1) simply displace the 5-diazo group; (2) couple to form a triazeno derivative; (3) react at the 5 position resulting in rearomatization or (4) react at the 5 position forming a 1, 6-dihydro product.

Some 5-diazouracil methanol adduct (XI) was reacted with dimethylamine according to the procedure described in Example I to give a product with elemental analysis consistent with the empirical formula C₆ H₉ N₅ O₂.

A proton magnetic resonance spectrum (DMSO-d₆) revealed a loss of the absorption peak for the methoxy group at δ 3.23 and the appearance of a peak at δ 3.20 for the dimethylamine moiety, a broad singlet (2 Protons) at δ 10.53 for the N-1 and N-3 protons and a downfield chemical shift (δ 7:10, singlet; Δ δ, 1.38) for the C-6 proton which indicated that C-6 was once again incorporated in a conjugated π electronic system. This established that the 5-diazo group had coupled with dimethylamine with the concomitant expulsion of methanol to produce a compound to which the structure 5-(3, 3-dimethyl-1-triazeno) uracil (V) was assigned.

The invention pertains, as indicated herein above, to compounds and to a process for producing said compounds. The reaction conducted according to the instant process involves stringent conditions, however, the conditions should not be so stringent as to cause significant ionization at the nitrogen atom in the three position. The pKa values for 5-diazouracil methanol adduct and 5-diazouridine are about 7.2 and 6.4, respectively. It is preferred that the reaction be conducted so that these values are not exceeded to any significant extent.

The pKa value is the pH at which the nitrogen in the three position is fifty percent ionized. As indicated herein above, the reaction must be conducted under conditions sufficiently stringent to break the C-O-C bond at the six position, however, it is preferred that the pH of the system be maintained less than the pKa value of the particular diazo reactant in order to avoid undesirable reaction products. 

We claim:
 1. The composition of matter having the structural formula ##STR9## wherein R is hydrogen or a carbohydrate group and R' and R" are lower alkyl groups.
 2. The composition of claim 1, wherein R is a monosaccaride group.
 3. The composition of claim 2, wherein R is a monosaccaride group having no more than six carbon atoms.
 4. The composition of claim 1 wherein R is a ribose group.
 5. The composition of claim 1, wherein R' and R" are methyl or ethyl groups.
 6. 5-(3,3-dimethyl-1-triazeno) uracil.
 7. 5-(3,3-dimethyl-1-triazeno) uridine.
 8. 5-(3,3-dimethyl-1-triazeno) 2'-deoxyuridine.
 9. 5-(3,3-diethyl-1-triazeno) uridine.
 10. The method of forming a triazeno compound having the structure ##STR10## wherein R is hydrogen or a carbohydrate group and R' and R" are lower alkyl groups, by reacting a dialkylamine with a compound having the structure ##STR11## wherein X and Y are H or X and Y is a carbohydrate group, said reaction conducted at a temperature at least 20° C and at a pH substantially below the pKa value of the nitrogen in the three position.
 11. The method of claim 10, wherein a solvent is present.
 12. The method of claim 10, wherein a fusion reaction is conducted.
 13. The method of claim 11, wherein the reaction is conducted under pressure.
 14. The method of claim 12, wherein the reaction is conducted under reflux conditions.
 15. The method of claim 11, wherein the solvent present is a non-polar solvent.
 16. The method of claim 10, wherein the dialkylamine is substantially non-ionizing. 